Dental instrument

ABSTRACT

A tooth-extracting instrument having a housing and including a pair of jaws having opposing beaks defining a plurality of spaced-apart tooth-engaging surfaces for complementary clamping engagement with opposite faces of a tooth to be extracted. One of the jaws is fixedly mounted on the housing. The other of the jaws is supported in generally parallel relation to the fixed jaw by the housing for movement generally toward and away from the fixed jaw in response to rotation of an axially elongated handle journaled by the housing. The movable jaw is further arranged for slight angular movement relative to the fixed jaw to permit the various tooth-engaging surfaces to be brought into positive clamping engagement with a tooth to be extracted in response to axial rotation of the handle.

United States Patent Rubino 1 Feb. 29, 1972 [54] DENTAL INSTRUMENT1,929,258 10/1933 Petersen et a]. .....8l/l64 [72] inventor: xii talctgmlno, 1088 N. Mam St., West Primary Examiner Roben PeshockAttorney-McCormick, Paulding & Huber [22] Filed: Nov. 16, 1970 [211App]. No.: 89,835 1571 ABSTRACT Related U.S. Application Data lo'ii Atooth-extracting instrument having a housing and including a pair ofjaws having opposing beaks defining a plurality of spaced-aparttooth-engaging surfaces for complementary clamping engagement withopposite faces of a tooth to be extracted. One of the jaws is fixedlymounted on the housing. The other of the jaws is supported in generallyparallel relation to the fixed jaw by the housing for movement generallytoward and away from the fixed jaw in response to rotation of an axiallyelongated handle journaled by the housing. The movable jaw is furtherarranged for slight angular movement relative to the fixed jaw to permitthe various tooth-engaging surfaces to be brought into positive clampingengagement with a tooth to be extracted in response to axial rotation ofthe handle.

14 Claims, 11 Drawing Figures Patented Feb. 29, 1972 3,644,998

2 Sheets-Shoot 1 0 van.

. INVENTOR.

VICTOR H. RUBINO ATTORNEYS Patented Feb. 29, 1972 3,644,998

2 Sheets-Shoot 2 DENTAL INSTRUMENT CROSS-REFERENCE TO RELATEDAPPLICATION This application is a continuation-in-part of pendingapplication, Ser. No. 829,187, filed June 2, 1969 and now abandoned, forDental Instrument."

BACKGROUND OF INVENTION This invention relates in general to dentalinstruments and deals more particularly with an instrument for use insurgical extraction of teeth.

In extracting a tooth using conventional extracting forceps having apair of pivoted handles, it is necessary for the dental surgeon tocontinually apply force to the handles to maintain the forceps ingripping engagement with a tooth to be extracted and to. simultaneouslyapply extracting force thereto. Since the beaks or tooth gripping partsof the instrument are usually arranged to pivot into engagement with atooth to be extracted, it will be evident that the instrument willordinarily engage the tooth at only two points, except in a special casewhen the beaks of the instrument happen to precisely complement thetooth. Any slipping or loosening of the gripping force on the tooth maycause the crown thereof to be broken off at or near the gum linerequiring surgical removal of the remaining portion of the tooth belowthe gum line or may cause excessive damage to the gum. Premature releaseof the tooth after extraction may result in the tooth becoming lodged inthe patient's esophagus or trachea, or in his sinus area. The risk ofpremature release is particularly severe when extraction is performedunder general anesthesia.

Accordingly, it is the general aim of the present invention to providean improved tooth extracting instrument which positively clampinglyengages a tooth to be extracted at a plurality of spaced points ofengagement in response to manipulation of a single handle. A further aimof the invention is to provide an improved dental instrumentof theaforedescribedcharacter arranged to clampingly engage a tooth in aposition which facilitates maximum visibility of the mouth area duringtooth extraction. Still another object of the invention is to providean-improved dental instrument having a jaw readily removable forcleaning, sterilization or replacement.

SUMMARY OF INVENTION In accordance with the present invention, a dentalinstrument is provided for use in surgical extraction of a tooth andincludes a body, a single axially elongated handle rotatably mounted onthe body, and a pair of clamping jaws. One jaw is fixedly mounted on thebody and the other jaw is supported by the body for movement relativethereto and generally toward and away from the fixed jaw. The jaws arearranged for movement in generally parallel relation into and out ofclamping engagement with a tooth to be extracted in response to rotationof the handle in one and the opposite direction. The movable jaw ispreferably supported and arranged for slight angular movement relativeto the fixed jaw to assure positive clamping engagement with the toothin response to rotation of the handle.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a side elevational view of adental instrument embodying the present invention and shows theinstrument in clamping engagement with a tooth.

FIG. 2 is a somewhat enlarged fragmentary elevational view of theinstrument of FIG. 1.

FIG. 3 is a sectional view taken along line 3-3 of FIG. 2.

FIG. 4 is a sectional view taken along line 4-4 of FIG. 3.

FIG. 5 is a sectional view taken along line 5-5 of FIG. 4.

FIG. 6 is a somewhat enlarged fragmentary side elevational view ofanother dental instrument embodying the present invention and shows theinstrument in clamping engagement with a tooth, portions of theinstrument being shown in longitudinal section.

2 FIG. 7 is a sectional view taken along the line 7-7 of FIG.

FIG. 8 is a sectional view taken along the line 8-8 of FIG.

FIG. 9 is a sectional view taken along line 9-9 of FIG. 6.

FIG. 10 is a sectional view taken along the line 10-10 of FIG. 6.

FIG. 11 is a sectional view taken along the line ll-ll of FIG. 6.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Turning now to thedrawing and referring particularly to FIG. 1, a dental instrumentembodying the present invention and indicated generally at 10 comprisesa body or hollow housing 12 and an axially elongated cylindrical: handle14 joumaled in the housing. The instrument 10 also has a pair ofclamping jaws which include a fixed jaw 18 mounted on the housing and amovable jaw 20 supported by the housing 12 for sliding movement relativethereto. The jaw 20 is movable generally toward and away from the fixedjaw 18 in response to axial rotation of the handle 14 in one and anopposite direction. In FIG. 1, the instrument It] is shown in clampingengagement with the crown portion of a tooth to be extracted indicatedat 22.

The housing 12 is preferably formed by two mating sections 24 and 26.The fixed jaw 18 forms an integral portion of the housing section 24 andprojects therefrom in a generally radial direction. The section 24 isotherwise substantially identical to the section 26. Each housingsection has inwardly opening recesses therein which cooperate to definean opening or chamber 28 and coaxially aligned front and rear bearingsurfaces respectively indicated at 30' and 32' which communicate withthe chamber 28 and provide journals for the handle. The housing sections24 and 26 also cooperate to define a bore 34 which extends through thehousing in parallel relation to the axis of the bearing surfaces 30 and32 and communicates with the chamber 28. The bore 34 has a generallyrectangular cross section and includes at least one inwardly projectingrib 36 which extends axially thereof. Preferably and as shown, threeribs 36, 36 are provided. The two housing sections are retained inassembly by a plurality of fasteners 38, 38.

Considering now the jaws in further detail, the movable jaw 20 isgenerally L-shaped and has an elongated portion 40 slidably received inthe bore 34 and another portion 35 which extends therefrom in generallyparallel alignment with the fixed jaw 18. The portion 40 has a generallyrectangular cross section complementing the cross section of the bore 34and a plurality of longitudinally extending grooves 42, 42 formedtherein and equal in number to the ribs 36, 36. Each groove 42 receivesan associated rib 36 therein to retain the movable jaw 20 in precisealignment with the fixed jaw 18. The jaw portion 40 also has a rack 44on its inner edge. Opposing recesses respectively formed in the free endportions or beaks of the jaws l8 and 20 define clamping surfaces 50 and52 for comrotation of the handle 14. A fastener 50 extends through theforward end of the housing and engages the handle 14 at its forward endto prevent axial movement of the handle relative to the housing.

The movable jaw 20 is preferably releasably retained in assembly withthe housing 12 so that it may be readily removed therefrom for cleaning,sterilization or replacement. A fastener 52 threaded into the rear endof the jaw 20 is arranged to abut the ribs 36, 36 when the jaw 20 ismoved to its fully opened position, and as best shown in FIG. 5. Whenthe fastener 52 is removed, the movable jaw 20 may be moved out ofassembly with the housing 12 by rotating the handle 14.

The enlarged gripping surface at the outer or free end portion of thehandle 14 has a diameter substantially greater than the major diameterof the worm gear 48 and facilitates application of substantial torque tothe worm gear 48. After the jaw surfaces 50 and 52 are brought intoclamping engagement with opposite'sides of a tooth crown, furtherrotation of the handle 14 causes a jammed or locked condition betweenthe rack 44 and the worm gear 48 which assures a positive grip on thetooth. Thereafter, it is only necessary for the dental surgeon to applyextracting force to the handle of the instrument to effect toothextraction.

Referring now to FIGS. 6-11, another tooth extracting instrumentembodying the present invention is indicated generally at 10a. Theinstrument 10a is similar in most respects to the instrument 10previously described. However, the preferred jaw structure isillustrated and described in somewhat further detail. Parts of theinstrument 10a which correspond to parts of the instrument 10 previouslydescribed bear the same reference numeral a letter a suffix and will notbe further described.

The instrument 10a has a fixed jaw 18a which comprises an integralportion of the housing section 240 and which extends from the housing12a in a generally radial direction. A movable jaw a is supported formovement generally toward and away from the fixed jaw 18a in response toaxial rotation of a handle 14a in one and in opposite direction. TheL-shaped movable jaw 20a has one portion 40a slidably received in thebore 34a and another portion 35a which extends from the forward end ofthe portion 40a in generally parallel alignment with the fixed jaw 18a.At least one rib 36a integrally formed on the housing 120 is received ina longitudinally extending groove 42a formed in the portion 40. Thelatter rib cooperates with the groove to maintain the movable jaw inalignment with the fixed jaw. However, it should be noted that someclearance is provided between the lower surface of the rib 36a and theupper surface of the groove 42a as indicated at 54 in FIG. 6. Thus, themovable jaw 20a is supported and arranged for slight angular movementrelative to the fixed jaw 180 between full and broken line positionssubstantially as shown. This arrangement permits the jaws 18a and 20a tobe brought into positive clamping engagement with a tooth such as 22a inresponse to rotation of the handle 14a, as will hereinafter be furtherevident.

Considering the jaws in further detail, the jaws 18a and 20a haveopposing beaks 56 and 58 at the outer ends thereof. At least one of thebeaks has a first tooth-engaging surface proximate the outer end thereoffor clamping engagement with one facial surface of the tooth 22a and asecond tooth-engaging surface spaced radially inwardly from the firsttooth-engaging surface for engagement with another portion of the tooth.The other of the beaks is provided with at least one tooth-engagingsurface for clamping engagement with the opposite facial surface of thetooth to be extracted. Preferably, and as shown, each of the beaks 56and 58 is provided with a plurality of spaced-apart tooth-engagingsurfaces for effecting clamping engagement with a tooth. Morespecifically, the beak 58 is provided with a first tooth-engagingsurface 60 proximate the outer end thereof for clamping engagement withthe tooth in the region of its dentoenamel junction or in the region ofthe junction between its root and crown. A second tooth-engaging surface62 spaced radially inwardly from the surface 60 is provided forengagement with an associated portion of the coronal belly of the tooth22a or in the central region of its crown. The beak 58 also includes athird tooth-engaging surface 64 spaced radially inwardly from thesurface 62 for engaging an associated portion of the tooth in the regionof its superior angle or near the upper portion of the crown. In likemanner, the beak 56 is provided with radially spaced-aparttooth-engaging surfaces respectively indicated at 66, 68 and 70 forengaging corresponding portions of the opposite facial surface of thetooth 22a. As shown, the beaks 56 and 58 have recesses formed thereinand respectively indicated at 50a and 5221 which define the varioustooth-engaging surfaces. The recesses 50a and 52a have arcuateconfigurations in mutually perpendicular planes substantially as shown.More specifically, it will be noted that the recesses 50a and 52a arearcuately contoured in vertical planes as shown in FIG. 6 and also inhorizontal planes as shown in FIGS. 7-9. Preferably, and as shown, eachrecess is generally anatomically contoured to conform to the shape of anassociated portion of a tooth to be extracted. The recesses cooperate todefine a tooth-receiving pocket therebetween when the tooth-engagingsurfaces are in engagement with a tooth be be extracted. Each of thebeaks is adapted to engage an associated facial surface portion of atooth such as 22a and to extend there beyond and toward the other of thebeaks on opposite sides of the tooth to at least partially surround thetooth, as best shown in FIGS. 6-8. The side portions of the beak 56which extend toward the beak 58 are indicated at 72, 72. The numerals74, 74 designate corresponding extending side portions of the beak 58.

When the instrument is used, the movable jaw 20a is first brought intoengagement with the lingual surface of the tooth to be extracted or thefacial surface of the tooth nearest the patients tongue. Thereafter, thehandle 14a is rotated to move the fixed jaw 18 into engagement with thelabial surface of the tooth or the facial surface nearest the patientslip. The slight relative angular motion between the fixed and movablejaw facilitated by the clearance 54 and clearance in the rack and pinionstructure permits the instrument to seat in clamping engagement with thetooth to be extracted to effect maximum engagement between the variousclamping surfaces and corresponding clamping regions on the tooth. Thus,for example, if the tooth is so shaped that the clamping surfaces 60 and66 tend to engage it at its dentoenamel junction before the otherclamping surfaces come into engagement with its crown, the slightangular movement of the movable jaw 20a will permit additionaltooth-engaging surfaces to be brought into contact with the crown. Thetooth may then be extracted by applying extracting movement to thesingle handle 14a to loosen the tooth from its attachment and ultimatelylift it from its socket.

lclaim:

l. A tooth-extracting instrument comprising a body, a single axiallyelongated handle joumaled for axial rotation at one end in said body andprojecting axially outwardly therefrom, a pair of jaws, one of said jawssupported in fixed relation to and extending generally radiallyoutwardly from said body, the other of said jaws supported by said bodyfor movement relative thereto and having one portion thereof associatedwith said body and another portion thereof extending generally radiallyoutwardly from said one portion in generally parallel alignment withsaid one jaw, said one jaw and said other portion having opposing beaksat the outer ends thereof, at least one of said beaks having a firsttooth-engaging surface proximate the outer end thereof for clampingengagement with one facial surface of the tooth to be extracted in theregion of its dentoenamel junction and a second tooth-engaging surfaceradially inwardly spaced from said first surface for engagement with anassociated portion of the crown of the tooth to be extracted when thetooth to be extracted is positioned between said beaks with its verticalaxis generally aligned in the radial direction relative to saidinstrument, the other of said beaks having at least one tooth-engagingsurface for clamping engagement with the opposite facial surface of thetooth to be extracted, and means associated with said single handle andoperatively engaging said other jaw for moving said other portiongenerally toward and away from said one jaw in parallel relation theretoin response to axial rotation of said handle in one and the oppositedirection relative to said body and for releasably retaining said otherportion in fixed position relative to said one jaw to secure saidtooth-engaging surfaces in releasable clamping engagement with the toothto be extracted to permit extraction thereof by manipulation of saidsingle handle.

2. A tooth-extracting instrument as set forth in claim 1 wherein saidone tooth-engaging surface is located proximate the outer end of saidother beak for engaging the other facial surface of the tooth to beextracted in the region of its dentoenamel junction and said other beakincludes another tooth-engaging surface radially inwardly spaced fromsaid one tooth-engaging surface for clampingly engaging as associatedportion of the crown of the tooth to be extracted.

3. A tooth-extracting instrument as set forth in claim 2 wherein saidsecond tooth-engaging surface and said other tooth-engaging surface arearranged to engage opposite facial surface portions of the tooth to beextracted in the region of its coronal belly, said one beak including athird tooth-engaging surface radially inwardly spaced from said secondtooth-engaging surface for engagement with the tooth to be extracted inthe region of its superior angle, said other beak including anadditional tooth-engaging surface radially inwardly spaced from saidother surface for engagement with the tooth to be extracted in theregion of its superior angle.

4. A tooth-extracting instrument as set forth in claim 2 wherein each ofsaid beaks has a recess formed therein having a generally arcuateconfiguration in mutually perpendicular planes and generallyanatomically contoured to conform to the shape of an associated portionof the tooth to be extracted, said recess in said one beak and saidrecess in said other beak defining said tooth-engaging surfaces.

5. A tooth-extracting instrument as set forth in claim 4 wherein saidrecess in said one beak and said recess in said other beak cooperate todefine a tooth-receiving pocket therebetween when said tooth-engagingsurfaces are in engagement with the tooth to be extracted, each of saidbeaks being adapted to engage an associated facial surface portion ofthe tooth to be extracted and to extend there beyond and toward theother of said beaks on opposite sides of the tooth to be extracted to atleast partially surround the tooth to be extracted.

6. A tooth-extracting instrument as set forth in claim 2 wherein saidother portion is supported and arranged for slight angular movementrelative to said one jaw to permit said tooth-engaging surfaces to bebrought into positive clamping engagement with the tooth to be extractedin response to axial rotation of said single handle.

7. A tooth-extracting instrument as set forth in claim 1 wherein saidbody comprises a hollow housing having a chamber therein, said means formoving said other portion operably engaging said one portion within saidchamber.

8. A tooth-extracting instrument as set forth in claim 7 wherein saidhousing comprises two mating sections, each of said sections havingrecesses therein, said recesses cooperating to define said chamber, apair of axially spaced, coaxially aligned bearing surfaces communicatingwith said chamber for journaling said one end, and a bore extendingthrough said housing in parallel relation to the axis of said bearingsurfaces and communicating with said chamber, said other portion beingslidably received in said bore.

9. A tooth-extracting instrument as set forth in claim 7 wherein saidmeans for moving said other portion comprises a rack formed on saidother portion and a worm gear on said handle and drivingly engaging saidrack.

10. A tooth-extracting instrument as set forth in claim 9 wherein saidhandle is generally cylindrical and the diameter of the outer portionthereof is substantially greater than the major diameter of said wormgear.

11. A tooth-extracting instrument as set forth in claim 9 wherein atleast one said sections has at least on rib formed therein projectinginto said bore and extending longitudinally thereof and said one portionhas at least one longitudinally extending groove therein receiving saidone rib to retain said other portion in alignment with said one jaw.

12. A tooth-extracting instrument as set forth in claim 1 includingmeans for releasably retaining said other jaw in assembly with saidbody.

13. A tooth-extracting instrument as set forth in claim 12 wherein saidmeans for releasably retaining said other jaw is a fastener threadablyengaging said one portion and adapted to engage an associated portion ofsaid body to limit movement of said other portion away from said onejaw, said other jaw being movable out of assembled relation with saidbody in response to rotation of said handle in said opposite directionwhen said fastener is removed from said one portion.

14. A dental instrument for surgically extracting a tooth comprising ahollow housing including two mating sections having a plurality ofrecesses formed therein and cooperating in assembly to define a chamber,an axially elongated bore extending therethrough and communicating withsaid chamber, and a pair of coaxially aligned cylindrical bearingsurfaces at opposite ends of said chamber, one of said sections havingan integral jaw extending radially outwardly therefrom including agenerally L-shaped jaw having one portion slidably received in saidbore, said one portion having a rack formed thereon, said other jawhaving another portion extending radially outwardly from the forward endof said one portion in generally parallel alignment with said integraljaw and having an arcuately rearwardly curving free end portion, saidfree end portions defining beaks having opposing recesses formed thereinadapted for generally complementary engagement with opposite surfaceportions of a tooth to be extracted when the tooth to be extracted isreceived therebetween with its vertical axis aligned in said radialdirection relative to said instrument, each of said recesses defining afirst tooth-engaging surface proximate the free end of an associated oneof said beaks for engagement with the tooth to be extracted proximateits dentoenamel junction, each of said recesses defining a secondtooth-engaging surface spaced radially inwardly from said firsttooth-engaging surface for engagement with an associated portion of thecrown of the tooth to be extracted, an axially elongated generallycylindrical handle having a forward end portion of reduced diameterextending into said housing and journaled by said bearing surfaces forcoaxial rotation therein, said forward end portion having a coaxial wormgear thereon disposed in said chamber and in driving engagement withsaid rack, said handle including a rearwardly extending portion having adiameter substantially greater than the major diameter of said wormgear, said other jaw being movable toward and away from said integraljaw in response to axial rotation of said handle in one and the oppositedirection respectively, and a fastener threadably received in said oneportion and adapted to engage an associated portion of said housing tolimit movement of said other jaw away from said integral jaw and toreleasably retain said other jaw in assembly with said housing, saidother jaw being movable out of assembled relation with said housing inresponse to rotation of said handle in said opposite direction when saidfastener is removed from said one portion.

1. A tooth-extracting instrument comprising a body, a single axiallyelongated handle journaled for axial rotation at one end in said bodyand projecting axially outwardly therefrom, a pair of jaws, one of saidjaws supported in fixed relation to and extending generally radiallyoutwardly from said body, the other of said jaws supported by said bodyfor movement relative thereto and having one portion thereof associatedwith said body and another portion thereof extending generally radiallyoutwardly from said one portion in generally parallel alignment withsaid one jaw, said one jaw and said other portion having opposing beaksat the outer ends thereof, at least one of said beaks having a firsttooth-engaging surface proximate the outer end thereof for clampingengagement with one facial surface of the tooth to be extracted in theregion of its dentoenamel junction and a second tooth-engaging surfaceradially inwardly spaced from said first surface for engagement with anassociated portion of the crown of the tooth to be extracted when thetooth to be extracted is positioned between said beaks with its verticalaxis generally aligned in the radial direction relative to saidinstrument, the other of said beaks having at least one toothengagingsurface for clamping engagement with the opposite facial surface of thetooth to be extracted, and means associated with said single handle andoperatively engaging said other jaw for moving said other portiongenerally toward and away from said one jaw in parallel relation theretoin response to axial rotation of said handle in one and the oppositedirection relative to said body and for releasably retaining said otherportion in fixed position relative to said one jaw to secure saidtooth-engaging surfaces in releasable clamping engagement with the toothto be extracted to permit extraction thereof by manipulation of saidsingle handle.
 2. A tooth-extracting instrument as set forth in claim 1wherein said one tooth-engaging surface is located proximate the outerend of said other beak for engaging the other facial surface of thetooth to be extracted in the region of its dentoenamel junction and saidother beak includes another tooth-engaging surface radially inwardlyspaced from said one tooth-engaging surface for clampingly engaging asassociated portion of the crown of the tooth to be extracted.
 3. Atooth-extracting instrument as set forth in claim 2 wherein said secondtooth-engaging surface and said other tooth-engaging surface arearranged to engage opposite facial surface portions of the tooth to beextracted in the region of its coronal belly, said one beak including athird tooth-engaging surface radially inwardly spaced from said secondtooth-engaging surface for engagement with the tooth to be extracted inthe region of its superior angle, said other beak including anadditional tooth-engaging surface radially inwardly spaced from saidother surface for engagement with the tooth to be extracted in theregion of its superior angle.
 4. A tooth-extracting instrument as setforth in claim 2 wherein each of said beaks has a recess formed thereinhaving a generally arcuate configuration in mutually perpendicularplanes and generally anatomically contoured to conform to the shape ofan associated portion of the tooth to be extracted, said recess in saidone beak and said recess in said other beak defining said tooth-engagingsurfaces.
 5. A tooth-extracting instrument as set forth in claim 4wherein said recess in said one beak and said recess in said other beakcooperate to define a tooth-receiving pocket therebetween when saidtooth-engaging surfaces are in engagement with the tooth to beextracted, each of said beaks being adapted to engage an associatedfacial surface portion of the tooth to be extracted and to extend therebeyond and toward the other of said beaks on opposite sides of the toothto be extracted to at least partially surround the tooth to beextracted.
 6. A tooth-extracting instrUment as set forth in claim 2wherein said other portion is supported and arranged for slight angularmovement relative to said one jaw to permit said tooth-engaging surfacesto be brought into positive clamping engagement with the tooth to beextracted in response to axial rotation of said single handle.
 7. Atooth-extracting instrument as set forth in claim 1 wherein said bodycomprises a hollow housing having a chamber therein, said means formoving said other portion operably engaging said one portion within saidchamber.
 8. A tooth-extracting instrument as set forth in claim 7wherein said housing comprises two mating sections, each of saidsections having recesses therein, said recesses cooperating to definesaid chamber, a pair of axially spaced, coaxially aligned bearingsurfaces communicating with said chamber for journaling said one end,and a bore extending through said housing in parallel relation to theaxis of said bearing surfaces and communicating with said chamber, saidother portion being slidably received in said bore.
 9. Atooth-extracting instrument as set forth in claim 7 wherein said meansfor moving said other portion comprises a rack formed on said otherportion and a worm gear on said handle and drivingly engaging said rack.10. A tooth-extracting instrument as set forth in claim 9 wherein saidhandle is generally cylindrical and the diameter of the outer portionthereof is substantially greater than the major diameter of said wormgear.
 11. A tooth-extracting instrument as set forth in claim 9 whereinat least one said sections has at least on rib formed therein projectinginto said bore and extending longitudinally thereof and said one portionhas at least one longitudinally extending groove therein receiving saidone rib to retain said other portion in alignment with said one jaw. 12.A tooth-extracting instrument as set forth in claim 1 including meansfor releasably retaining said other jaw in assembly with said body. 13.A tooth-extracting instrument as set forth in claim 12 wherein saidmeans for releasably retaining said other jaw is a fastener threadablyengaging said one portion and adapted to engage an associated portion ofsaid body to limit movement of said other portion away from said onejaw, said other jaw being movable out of assembled relation with saidbody in response to rotation of said handle in said opposite directionwhen said fastener is removed from said one portion.
 14. A dentalinstrument for surgically extracting a tooth comprising a hollow housingincluding two mating sections having a plurality of recesses formedtherein and cooperating in assembly to define a chamber, an axiallyelongated bore extending therethrough and communicating with saidchamber, and a pair of coaxially aligned cylindrical bearing surfaces atopposite ends of said chamber, one of said sections having an integraljaw extending radially outwardly therefrom including a generallyL-shaped jaw having one portion slidably received in said bore, said oneportion having a rack formed thereon, said other jaw having anotherportion extending radially outwardly from the forward end of said oneportion in generally parallel alignment with said integral jaw andhaving an arcuately rearwardly curving free end portion, said free endportions defining beaks having opposing recesses formed therein adaptedfor generally complementary engagement with opposite surface portions ofa tooth to be extracted when the tooth to be extracted is receivedtherebetween with its vertical axis aligned in said radial directionrelative to said instrument, each of said recesses defining a firsttooth-engaging surface proximate the free end of an associated one ofsaid beaks for engagement with the tooth to be extracted proximate itsdentoenamel junction, each of said recesses defining a secondtooth-engaging surface spaced radially inwardly from said firsttooth-engaging surface for engagement with an associated portion of thecrown of the tooth to be exTracted, an axially elongated generallycylindrical handle having a forward end portion of reduced diameterextending into said housing and journaled by said bearing surfaces forcoaxial rotation therein, said forward end portion having a coaxial wormgear thereon disposed in said chamber and in driving engagement withsaid rack, said handle including a rearwardly extending portion having adiameter substantially greater than the major diameter of said wormgear, said other jaw being movable toward and away from said integraljaw in response to axial rotation of said handle in one and the oppositedirection respectively, and a fastener threadably received in said oneportion and adapted to engage an associated portion of said housing tolimit movement of said other jaw away from said integral jaw and toreleasably retain said other jaw in assembly with said housing, saidother jaw being movable out of assembled relation with said housing inresponse to rotation of said handle in said opposite direction when saidfastener is removed from said one portion.